1 /*-
2 * Copyright (c) 2001-2002 Packet Design, LLC.
3 * All rights reserved.
4 *
5 * Subject to the following obligations and disclaimer of warranty,
6 * use and redistribution of this software, in source or object code
7 * forms, with or without modifications are expressly permitted by
8 * Packet Design; provided, however, that:
9 *
10 * (i) Any and all reproductions of the source or object code
11 * must include the copyright notice above and the following
12 * disclaimer of warranties; and
13 * (ii) No rights are granted, in any manner or form, to use
14 * Packet Design trademarks, including the mark "PACKET DESIGN"
15 * on advertising, endorsements, or otherwise except as such
16 * appears in the above copyright notice or in the software.
17 *
18 * THIS SOFTWARE IS BEING PROVIDED BY PACKET DESIGN "AS IS", AND
19 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, PACKET DESIGN MAKES NO
20 * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING
21 * THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED
22 * WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE,
23 * OR NON-INFRINGEMENT. PACKET DESIGN DOES NOT WARRANT, GUARANTEE,
24 * OR MAKE ANY REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS
25 * OF THE USE OF THIS SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY,
26 * RELIABILITY OR OTHERWISE. IN NO EVENT SHALL PACKET DESIGN BE
27 * LIABLE FOR ANY DAMAGES RESULTING FROM OR ARISING OUT OF ANY USE
28 * OF THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, ANY DIRECT,
29 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, PUNITIVE, OR CONSEQUENTIAL
30 * DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, LOSS OF
31 * USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY THEORY OF
32 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
34 * THE USE OF THIS SOFTWARE, EVEN IF PACKET DESIGN IS ADVISED OF
35 * THE POSSIBILITY OF SUCH DAMAGE.
36 *
37 * Author: Archie Cobbs <archie@freebsd.org>
38 *
39 * $FreeBSD$
40 */
41
42 /*
43 * L2TP netgraph node type.
44 *
45 * This node type implements the lower layer of the
46 * L2TP protocol as specified in RFC 2661.
47 */
48
49 #include <sys/param.h>
50 #include <sys/systm.h>
51 #include <sys/kernel.h>
52 #include <sys/time.h>
53 #include <sys/conf.h>
54 #include <sys/mbuf.h>
55 #include <sys/malloc.h>
56 #include <sys/errno.h>
57 #include <sys/libkern.h>
58
59 #include <netgraph/ng_message.h>
60 #include <netgraph/netgraph.h>
61 #include <netgraph/ng_parse.h>
62 #include <netgraph/ng_l2tp.h>
63
64 #ifdef NG_SEPARATE_MALLOC
65 MALLOC_DEFINE(M_NETGRAPH_L2TP, "netgraph_l2tp", "netgraph l2tp node");
66 #else
67 #define M_NETGRAPH_L2TP M_NETGRAPH
68 #endif
69
70 /* L2TP header format (first 2 bytes only) */
71 #define L2TP_HDR_CTRL 0x8000 /* control packet */
72 #define L2TP_HDR_LEN 0x4000 /* has length field */
73 #define L2TP_HDR_SEQ 0x0800 /* has ns, nr fields */
74 #define L2TP_HDR_OFF 0x0200 /* has offset field */
75 #define L2TP_HDR_PRIO 0x0100 /* give priority */
76 #define L2TP_HDR_VERS_MASK 0x000f /* version field mask */
77 #define L2TP_HDR_VERSION 0x0002 /* version field */
78
79 /* Bits that must be zero or one in first two bytes of header */
80 #define L2TP_CTRL_0BITS 0x030d /* ctrl: must be 0 */
81 #define L2TP_CTRL_1BITS 0xc802 /* ctrl: must be 1 */
82 #define L2TP_DATA_0BITS 0x800d /* data: must be 0 */
83 #define L2TP_DATA_1BITS 0x0002 /* data: must be 1 */
84
85 /* Standard xmit ctrl and data header bits */
86 #define L2TP_CTRL_HDR (L2TP_HDR_CTRL | L2TP_HDR_LEN \
87 | L2TP_HDR_SEQ | L2TP_HDR_VERSION)
88 #define L2TP_DATA_HDR (L2TP_HDR_VERSION) /* optional: len, seq */
89
90 /* Some hard coded values */
91 #define L2TP_MAX_XWIN 128 /* my max xmit window */
92 #define L2TP_MAX_REXMIT 5 /* default max rexmit */
93 #define L2TP_MAX_REXMIT_TO 30 /* default rexmit to */
94 #define L2TP_DELAYED_ACK ((hz + 19) / 20) /* delayed ack: 50 ms */
95
96 /* Default data sequence number configuration for new sessions */
97 #define L2TP_CONTROL_DSEQ 1 /* we are the lns */
98 #define L2TP_ENABLE_DSEQ 1 /* enable data seq # */
99
100 /* Compare sequence numbers using circular math */
101 #define L2TP_SEQ_DIFF(x, y) ((int)((int16_t)(x) - (int16_t)(y)))
102
103 #define SESSHASHSIZE 0x0020
104 #define SESSHASH(x) (((x) ^ ((x) >> 8)) & (SESSHASHSIZE - 1))
105
106 /* Hook private data (data session hooks only) */
107 struct ng_l2tp_hook_private {
108 struct ng_l2tp_sess_config conf; /* hook/session config */
109 struct ng_l2tp_session_stats stats; /* per sessions statistics */
110 hook_p hook; /* hook reference */
111 u_int16_t ns; /* data ns sequence number */
112 u_int16_t nr; /* data nr sequence number */
113 LIST_ENTRY(ng_l2tp_hook_private) sessions;
114 };
115 typedef struct ng_l2tp_hook_private *hookpriv_p;
116
117 /*
118 * Sequence number state
119 *
120 * Invariants:
121 * - If cwnd < ssth, we're doing slow start, otherwise congestion avoidance
122 * - The number of unacknowledged xmit packets is (ns - rack) <= seq->wmax
123 * - The first (ns - rack) mbuf's in xwin[] array are copies of these
124 * unacknowledged packets; the remainder of xwin[] consists first of
125 * zero or more further untransmitted packets in the transmit queue
126 * - We try to keep the peer's receive window as full as possible.
127 * Therefore, (i < cwnd && xwin[i] != NULL) implies (ns - rack) > i.
128 * - rack_timer is running iff (ns - rack) > 0 (unack'd xmit'd pkts)
129 * - If xack != nr, there are unacknowledged recv packet(s) (delayed ack)
130 * - xack_timer is running iff xack != nr (unack'd rec'd pkts)
131 */
132 struct l2tp_seq {
133 u_int16_t ns; /* next xmit seq we send */
134 u_int16_t nr; /* next recv seq we expect */
135 u_int16_t inproc; /* packet is in processing */
136 u_int16_t rack; /* last 'nr' we rec'd */
137 u_int16_t xack; /* last 'nr' we sent */
138 u_int16_t wmax; /* peer's max recv window */
139 u_int16_t cwnd; /* current congestion window */
140 u_int16_t ssth; /* slow start threshold */
141 u_int16_t acks; /* # consecutive acks rec'd */
142 u_int16_t rexmits; /* # retransmits sent */
143 struct callout rack_timer; /* retransmit timer */
144 struct callout xack_timer; /* delayed ack timer */
145 struct mbuf *xwin[L2TP_MAX_XWIN]; /* transmit window */
146 struct mtx mtx; /* seq mutex */
147 };
148
149 /* Node private data */
150 struct ng_l2tp_private {
151 node_p node; /* back pointer to node */
152 hook_p ctrl; /* hook to upper layers */
153 hook_p lower; /* hook to lower layers */
154 struct ng_l2tp_config conf; /* node configuration */
155 struct ng_l2tp_stats stats; /* node statistics */
156 struct l2tp_seq seq; /* ctrl sequence number state */
157 ng_ID_t ftarget; /* failure message target */
158 LIST_HEAD(, ng_l2tp_hook_private) sesshash[SESSHASHSIZE];
159 };
160 typedef struct ng_l2tp_private *priv_p;
161
162 /* Netgraph node methods */
163 static ng_constructor_t ng_l2tp_constructor;
164 static ng_rcvmsg_t ng_l2tp_rcvmsg;
165 static ng_shutdown_t ng_l2tp_shutdown;
166 static ng_newhook_t ng_l2tp_newhook;
167 static ng_rcvdata_t ng_l2tp_rcvdata;
168 static ng_rcvdata_t ng_l2tp_rcvdata_lower;
169 static ng_rcvdata_t ng_l2tp_rcvdata_ctrl;
170 static ng_disconnect_t ng_l2tp_disconnect;
171
172 /* Internal functions */
173 static int ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns);
174
175 static void ng_l2tp_seq_init(priv_p priv);
176 static int ng_l2tp_seq_set(priv_p priv,
177 const struct ng_l2tp_seq_config *conf);
178 static int ng_l2tp_seq_adjust(priv_p priv,
179 const struct ng_l2tp_config *conf);
180 static void ng_l2tp_seq_reset(priv_p priv);
181 static void ng_l2tp_seq_failure(priv_p priv);
182 static void ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr);
183 static void ng_l2tp_seq_xack_timeout(node_p node, hook_p hook,
184 void *arg1, int arg2);
185 static void ng_l2tp_seq_rack_timeout(node_p node, hook_p hook,
186 void *arg1, int arg2);
187
188 static hookpriv_p ng_l2tp_find_session(priv_p privp, u_int16_t sid);
189 static ng_fn_eachhook ng_l2tp_reset_session;
190
191 #ifdef INVARIANTS
192 static void ng_l2tp_seq_check(struct l2tp_seq *seq);
193 #endif
194
195 /* Parse type for struct ng_l2tp_seq_config. */
196 static const struct ng_parse_struct_field
197 ng_l2tp_seq_config_fields[] = NG_L2TP_SEQ_CONFIG_TYPE_INFO;
198 static const struct ng_parse_type ng_l2tp_seq_config_type = {
199 &ng_parse_struct_type,
200 &ng_l2tp_seq_config_fields
201 };
202
203 /* Parse type for struct ng_l2tp_config */
204 static const struct ng_parse_struct_field
205 ng_l2tp_config_type_fields[] = NG_L2TP_CONFIG_TYPE_INFO;
206 static const struct ng_parse_type ng_l2tp_config_type = {
207 &ng_parse_struct_type,
208 &ng_l2tp_config_type_fields,
209 };
210
211 /* Parse type for struct ng_l2tp_sess_config */
212 static const struct ng_parse_struct_field
213 ng_l2tp_sess_config_type_fields[] = NG_L2TP_SESS_CONFIG_TYPE_INFO;
214 static const struct ng_parse_type ng_l2tp_sess_config_type = {
215 &ng_parse_struct_type,
216 &ng_l2tp_sess_config_type_fields,
217 };
218
219 /* Parse type for struct ng_l2tp_stats */
220 static const struct ng_parse_struct_field
221 ng_l2tp_stats_type_fields[] = NG_L2TP_STATS_TYPE_INFO;
222 static const struct ng_parse_type ng_l2tp_stats_type = {
223 &ng_parse_struct_type,
224 &ng_l2tp_stats_type_fields
225 };
226
227 /* Parse type for struct ng_l2tp_session_stats. */
228 static const struct ng_parse_struct_field
229 ng_l2tp_session_stats_type_fields[] = NG_L2TP_SESSION_STATS_TYPE_INFO;
230 static const struct ng_parse_type ng_l2tp_session_stats_type = {
231 &ng_parse_struct_type,
232 &ng_l2tp_session_stats_type_fields
233 };
234
235 /* List of commands and how to convert arguments to/from ASCII */
236 static const struct ng_cmdlist ng_l2tp_cmdlist[] = {
237 {
238 NGM_L2TP_COOKIE,
239 NGM_L2TP_SET_CONFIG,
240 "setconfig",
241 &ng_l2tp_config_type,
242 NULL
243 },
244 {
245 NGM_L2TP_COOKIE,
246 NGM_L2TP_GET_CONFIG,
247 "getconfig",
248 NULL,
249 &ng_l2tp_config_type
250 },
251 {
252 NGM_L2TP_COOKIE,
253 NGM_L2TP_SET_SESS_CONFIG,
254 "setsessconfig",
255 &ng_l2tp_sess_config_type,
256 NULL
257 },
258 {
259 NGM_L2TP_COOKIE,
260 NGM_L2TP_GET_SESS_CONFIG,
261 "getsessconfig",
262 &ng_parse_hint16_type,
263 &ng_l2tp_sess_config_type
264 },
265 {
266 NGM_L2TP_COOKIE,
267 NGM_L2TP_GET_STATS,
268 "getstats",
269 NULL,
270 &ng_l2tp_stats_type
271 },
272 {
273 NGM_L2TP_COOKIE,
274 NGM_L2TP_CLR_STATS,
275 "clrstats",
276 NULL,
277 NULL
278 },
279 {
280 NGM_L2TP_COOKIE,
281 NGM_L2TP_GETCLR_STATS,
282 "getclrstats",
283 NULL,
284 &ng_l2tp_stats_type
285 },
286 {
287 NGM_L2TP_COOKIE,
288 NGM_L2TP_GET_SESSION_STATS,
289 "getsessstats",
290 &ng_parse_int16_type,
291 &ng_l2tp_session_stats_type
292 },
293 {
294 NGM_L2TP_COOKIE,
295 NGM_L2TP_CLR_SESSION_STATS,
296 "clrsessstats",
297 &ng_parse_int16_type,
298 NULL
299 },
300 {
301 NGM_L2TP_COOKIE,
302 NGM_L2TP_GETCLR_SESSION_STATS,
303 "getclrsessstats",
304 &ng_parse_int16_type,
305 &ng_l2tp_session_stats_type
306 },
307 {
308 NGM_L2TP_COOKIE,
309 NGM_L2TP_ACK_FAILURE,
310 "ackfailure",
311 NULL,
312 NULL
313 },
314 {
315 NGM_L2TP_COOKIE,
316 NGM_L2TP_SET_SEQ,
317 "setsequence",
318 &ng_l2tp_seq_config_type,
319 NULL
320 },
321 { 0 }
322 };
323
324 /* Node type descriptor */
325 static struct ng_type ng_l2tp_typestruct = {
326 .version = NG_ABI_VERSION,
327 .name = NG_L2TP_NODE_TYPE,
328 .constructor = ng_l2tp_constructor,
329 .rcvmsg = ng_l2tp_rcvmsg,
330 .shutdown = ng_l2tp_shutdown,
331 .newhook = ng_l2tp_newhook,
332 .rcvdata = ng_l2tp_rcvdata,
333 .disconnect = ng_l2tp_disconnect,
334 .cmdlist = ng_l2tp_cmdlist,
335 };
336 NETGRAPH_INIT(l2tp, &ng_l2tp_typestruct);
337
338 /* Sequence number state sanity checking */
339 #ifdef INVARIANTS
340 #define L2TP_SEQ_CHECK(seq) ng_l2tp_seq_check(seq)
341 #else
342 #define L2TP_SEQ_CHECK(x) do { } while (0)
343 #endif
344
345 /* memmove macro */
346 #define memmove(d, s, l) bcopy(s, d, l)
347
348 /* Whether to use m_copypacket() or m_dup() */
349 #define L2TP_COPY_MBUF m_copypacket
350
351 #define ERROUT(x) do { error = (x); goto done; } while (0)
352
353 /************************************************************************
354 NETGRAPH NODE STUFF
355 ************************************************************************/
356
357 /*
358 * Node type constructor
359 */
360 static int
361 ng_l2tp_constructor(node_p node)
362 {
363 priv_p priv;
364 int i;
365
366 /* Allocate private structure */
367 MALLOC(priv, priv_p, sizeof(*priv), M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO);
368 if (priv == NULL)
369 return (ENOMEM);
370 NG_NODE_SET_PRIVATE(node, priv);
371 priv->node = node;
372
373 /* Apply a semi-reasonable default configuration */
374 priv->conf.peer_win = 1;
375 priv->conf.rexmit_max = L2TP_MAX_REXMIT;
376 priv->conf.rexmit_max_to = L2TP_MAX_REXMIT_TO;
377
378 /* Initialize sequence number state */
379 ng_l2tp_seq_init(priv);
380
381 for (i = 0; i < SESSHASHSIZE; i++)
382 LIST_INIT(&priv->sesshash[i]);
383
384 /* Done */
385 return (0);
386 }
387
388 /*
389 * Give our OK for a hook to be added.
390 */
391 static int
392 ng_l2tp_newhook(node_p node, hook_p hook, const char *name)
393 {
394 const priv_p priv = NG_NODE_PRIVATE(node);
395
396 /* Check hook name */
397 if (strcmp(name, NG_L2TP_HOOK_CTRL) == 0) {
398 if (priv->ctrl != NULL)
399 return (EISCONN);
400 priv->ctrl = hook;
401 NG_HOOK_SET_RCVDATA(hook, ng_l2tp_rcvdata_ctrl);
402 } else if (strcmp(name, NG_L2TP_HOOK_LOWER) == 0) {
403 if (priv->lower != NULL)
404 return (EISCONN);
405 priv->lower = hook;
406 NG_HOOK_SET_RCVDATA(hook, ng_l2tp_rcvdata_lower);
407 } else {
408 static const char hexdig[16] = "0123456789abcdef";
409 u_int16_t session_id;
410 hookpriv_p hpriv;
411 uint16_t hash;
412 const char *hex;
413 int i;
414 int j;
415
416 /* Parse hook name to get session ID */
417 if (strncmp(name, NG_L2TP_HOOK_SESSION_P,
418 sizeof(NG_L2TP_HOOK_SESSION_P) - 1) != 0)
419 return (EINVAL);
420 hex = name + sizeof(NG_L2TP_HOOK_SESSION_P) - 1;
421 for (session_id = i = 0; i < 4; i++) {
422 for (j = 0; j < 16 && hex[i] != hexdig[j]; j++);
423 if (j == 16)
424 return (EINVAL);
425 session_id = (session_id << 4) | j;
426 }
427 if (hex[i] != '\0')
428 return (EINVAL);
429
430 /* Create hook private structure */
431 MALLOC(hpriv, hookpriv_p,
432 sizeof(*hpriv), M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO);
433 if (hpriv == NULL)
434 return (ENOMEM);
435 hpriv->conf.session_id = session_id;
436 hpriv->conf.control_dseq = L2TP_CONTROL_DSEQ;
437 hpriv->conf.enable_dseq = L2TP_ENABLE_DSEQ;
438 hpriv->hook = hook;
439 NG_HOOK_SET_PRIVATE(hook, hpriv);
440 hash = SESSHASH(hpriv->conf.session_id);
441 LIST_INSERT_HEAD(&priv->sesshash[hash], hpriv, sessions);
442 }
443
444 /* Done */
445 return (0);
446 }
447
448 /*
449 * Receive a control message.
450 */
451 static int
452 ng_l2tp_rcvmsg(node_p node, item_p item, hook_p lasthook)
453 {
454 const priv_p priv = NG_NODE_PRIVATE(node);
455 struct ng_mesg *resp = NULL;
456 struct ng_mesg *msg;
457 int error = 0;
458
459 NGI_GET_MSG(item, msg);
460 switch (msg->header.typecookie) {
461 case NGM_L2TP_COOKIE:
462 switch (msg->header.cmd) {
463 case NGM_L2TP_SET_CONFIG:
464 {
465 struct ng_l2tp_config *const conf =
466 (struct ng_l2tp_config *)msg->data;
467
468 /* Check for invalid or illegal config */
469 if (msg->header.arglen != sizeof(*conf)) {
470 error = EINVAL;
471 break;
472 }
473 conf->enabled = !!conf->enabled;
474 conf->match_id = !!conf->match_id;
475 if (priv->conf.enabled
476 && ((priv->conf.tunnel_id != 0
477 && conf->tunnel_id != priv->conf.tunnel_id)
478 || ((priv->conf.peer_id != 0
479 && conf->peer_id != priv->conf.peer_id)))) {
480 error = EBUSY;
481 break;
482 }
483
484 /* Save calling node as failure target */
485 priv->ftarget = NGI_RETADDR(item);
486
487 /* Adjust sequence number state */
488 if ((error = ng_l2tp_seq_adjust(priv, conf)) != 0)
489 break;
490
491 /* Update node's config */
492 priv->conf = *conf;
493 break;
494 }
495 case NGM_L2TP_GET_CONFIG:
496 {
497 struct ng_l2tp_config *conf;
498
499 NG_MKRESPONSE(resp, msg, sizeof(*conf), M_NOWAIT);
500 if (resp == NULL) {
501 error = ENOMEM;
502 break;
503 }
504 conf = (struct ng_l2tp_config *)resp->data;
505 *conf = priv->conf;
506 break;
507 }
508 case NGM_L2TP_SET_SESS_CONFIG:
509 {
510 struct ng_l2tp_sess_config *const conf =
511 (struct ng_l2tp_sess_config *)msg->data;
512 hookpriv_p hpriv;
513
514 /* Check for invalid or illegal config. */
515 if (msg->header.arglen != sizeof(*conf)) {
516 error = EINVAL;
517 break;
518 }
519
520 /* Find matching hook */
521 hpriv = ng_l2tp_find_session(priv, conf->session_id);
522 if (hpriv == NULL) {
523 error = ENOENT;
524 break;
525 }
526
527 /* Update hook's config */
528 hpriv->conf = *conf;
529 break;
530 }
531 case NGM_L2TP_GET_SESS_CONFIG:
532 {
533 struct ng_l2tp_sess_config *conf;
534 u_int16_t session_id;
535 hookpriv_p hpriv;
536
537 /* Get session ID */
538 if (msg->header.arglen != sizeof(session_id)) {
539 error = EINVAL;
540 break;
541 }
542 memcpy(&session_id, msg->data, 2);
543
544 /* Find matching hook */
545 hpriv = ng_l2tp_find_session(priv, session_id);
546 if (hpriv == NULL) {
547 error = ENOENT;
548 break;
549 }
550
551 /* Send response */
552 NG_MKRESPONSE(resp, msg, sizeof(hpriv->conf), M_NOWAIT);
553 if (resp == NULL) {
554 error = ENOMEM;
555 break;
556 }
557 conf = (struct ng_l2tp_sess_config *)resp->data;
558 *conf = hpriv->conf;
559 break;
560 }
561 case NGM_L2TP_GET_STATS:
562 case NGM_L2TP_CLR_STATS:
563 case NGM_L2TP_GETCLR_STATS:
564 {
565 if (msg->header.cmd != NGM_L2TP_CLR_STATS) {
566 NG_MKRESPONSE(resp, msg,
567 sizeof(priv->stats), M_NOWAIT);
568 if (resp == NULL) {
569 error = ENOMEM;
570 break;
571 }
572 memcpy(resp->data,
573 &priv->stats, sizeof(priv->stats));
574 }
575 if (msg->header.cmd != NGM_L2TP_GET_STATS)
576 memset(&priv->stats, 0, sizeof(priv->stats));
577 break;
578 }
579 case NGM_L2TP_GET_SESSION_STATS:
580 case NGM_L2TP_CLR_SESSION_STATS:
581 case NGM_L2TP_GETCLR_SESSION_STATS:
582 {
583 uint16_t session_id;
584 hookpriv_p hpriv;
585
586 /* Get session ID. */
587 if (msg->header.arglen != sizeof(session_id)) {
588 error = EINVAL;
589 break;
590 }
591 bcopy(msg->data, &session_id, sizeof(uint16_t));
592
593 /* Find matching hook. */
594 hpriv = ng_l2tp_find_session(priv, session_id);
595 if (hpriv == NULL) {
596 error = ENOENT;
597 break;
598 }
599
600 if (msg->header.cmd != NGM_L2TP_CLR_SESSION_STATS) {
601 NG_MKRESPONSE(resp, msg,
602 sizeof(hpriv->stats), M_NOWAIT);
603 if (resp == NULL) {
604 error = ENOMEM;
605 break;
606 }
607 bcopy(&hpriv->stats, resp->data,
608 sizeof(hpriv->stats));
609 }
610 if (msg->header.cmd != NGM_L2TP_GET_SESSION_STATS)
611 bzero(&hpriv->stats, sizeof(hpriv->stats));
612 break;
613 }
614 case NGM_L2TP_SET_SEQ:
615 {
616 struct ng_l2tp_seq_config *const conf =
617 (struct ng_l2tp_seq_config *)msg->data;
618
619 /* Check for invalid or illegal seq config. */
620 if (msg->header.arglen != sizeof(*conf)) {
621 error = EINVAL;
622 break;
623 }
624 conf->ns = htons(conf->ns);
625 conf->nr = htons(conf->nr);
626 conf->rack = htons(conf->rack);
627 conf->xack = htons(conf->xack);
628
629 /* Set sequence numbers. */
630 error = ng_l2tp_seq_set(priv, conf);
631 break;
632 }
633 default:
634 error = EINVAL;
635 break;
636 }
637 break;
638 default:
639 error = EINVAL;
640 break;
641 }
642
643 /* Done */
644 NG_RESPOND_MSG(error, node, item, resp);
645 NG_FREE_MSG(msg);
646 return (error);
647 }
648
649 /*
650 * Destroy node
651 */
652 static int
653 ng_l2tp_shutdown(node_p node)
654 {
655 const priv_p priv = NG_NODE_PRIVATE(node);
656 struct l2tp_seq *const seq = &priv->seq;
657
658 /* Sanity check */
659 L2TP_SEQ_CHECK(seq);
660
661 /* Reset sequence number state */
662 ng_l2tp_seq_reset(priv);
663
664 /* Free private data if neither timer is running */
665 ng_uncallout(&seq->rack_timer, node);
666 ng_uncallout(&seq->xack_timer, node);
667
668 mtx_destroy(&seq->mtx);
669
670 FREE(priv, M_NETGRAPH_L2TP);
671
672 /* Unref node */
673 NG_NODE_UNREF(node);
674 return (0);
675 }
676
677 /*
678 * Hook disconnection
679 */
680 static int
681 ng_l2tp_disconnect(hook_p hook)
682 {
683 const node_p node = NG_HOOK_NODE(hook);
684 const priv_p priv = NG_NODE_PRIVATE(node);
685
686 /* Zero out hook pointer */
687 if (hook == priv->ctrl)
688 priv->ctrl = NULL;
689 else if (hook == priv->lower)
690 priv->lower = NULL;
691 else {
692 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
693 LIST_REMOVE(hpriv, sessions);
694 FREE(hpriv, M_NETGRAPH_L2TP);
695 NG_HOOK_SET_PRIVATE(hook, NULL);
696 }
697
698 /* Go away if no longer connected to anything */
699 if (NG_NODE_NUMHOOKS(node) == 0 && NG_NODE_IS_VALID(node))
700 ng_rmnode_self(node);
701 return (0);
702 }
703
704 /*************************************************************************
705 INTERNAL FUNCTIONS
706 *************************************************************************/
707
708 /*
709 * Find the hook with a given session ID.
710 */
711 static hookpriv_p
712 ng_l2tp_find_session(priv_p privp, u_int16_t sid)
713 {
714 uint16_t hash = SESSHASH(sid);
715 hookpriv_p hpriv = NULL;
716
717 LIST_FOREACH(hpriv, &privp->sesshash[hash], sessions) {
718 if (hpriv->conf.session_id == sid)
719 break;
720 }
721
722 return (hpriv);
723 }
724
725 /*
726 * Reset a hook's session state.
727 */
728 static int
729 ng_l2tp_reset_session(hook_p hook, void *arg)
730 {
731 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
732
733 if (hpriv != NULL) {
734 hpriv->conf.control_dseq = 0;
735 hpriv->conf.enable_dseq = 0;
736 bzero(&hpriv->stats, sizeof(struct ng_l2tp_session_stats));
737 hpriv->nr = 0;
738 hpriv->ns = 0;
739 }
740 return (-1);
741 }
742
743 /*
744 * Handle an incoming frame from below.
745 */
746 static int
747 ng_l2tp_rcvdata_lower(hook_p h, item_p item)
748 {
749 static const u_int16_t req_bits[2][2] = {
750 { L2TP_DATA_0BITS, L2TP_DATA_1BITS },
751 { L2TP_CTRL_0BITS, L2TP_CTRL_1BITS },
752 };
753 const node_p node = NG_HOOK_NODE(h);
754 const priv_p priv = NG_NODE_PRIVATE(node);
755 hookpriv_p hpriv = NULL;
756 hook_p hook = NULL;
757 struct mbuf *m;
758 u_int16_t tid, sid;
759 u_int16_t hdr;
760 u_int16_t ns, nr;
761 int is_ctrl;
762 int error;
763 int len, plen;
764
765 /* Sanity check */
766 L2TP_SEQ_CHECK(&priv->seq);
767
768 /* If not configured, reject */
769 if (!priv->conf.enabled) {
770 NG_FREE_ITEM(item);
771 ERROUT(ENXIO);
772 }
773
774 /* Grab mbuf */
775 NGI_GET_M(item, m);
776
777 /* Remember full packet length; needed for per session accounting. */
778 plen = m->m_pkthdr.len;
779
780 /* Update stats */
781 priv->stats.recvPackets++;
782 priv->stats.recvOctets += plen;
783
784 /* Get initial header */
785 if (m->m_pkthdr.len < 6) {
786 priv->stats.recvRunts++;
787 NG_FREE_ITEM(item);
788 NG_FREE_M(m);
789 ERROUT(EINVAL);
790 }
791 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
792 priv->stats.memoryFailures++;
793 NG_FREE_ITEM(item);
794 ERROUT(EINVAL);
795 }
796 hdr = ntohs(*mtod(m, u_int16_t *));
797 m_adj(m, 2);
798
799 /* Check required header bits and minimum length */
800 is_ctrl = (hdr & L2TP_HDR_CTRL) != 0;
801 if ((hdr & req_bits[is_ctrl][0]) != 0
802 || (~hdr & req_bits[is_ctrl][1]) != 0) {
803 priv->stats.recvInvalid++;
804 NG_FREE_ITEM(item);
805 NG_FREE_M(m);
806 ERROUT(EINVAL);
807 }
808 if (m->m_pkthdr.len < 4 /* tunnel, session id */
809 + (2 * ((hdr & L2TP_HDR_LEN) != 0)) /* length field */
810 + (4 * ((hdr & L2TP_HDR_SEQ) != 0)) /* seq # fields */
811 + (2 * ((hdr & L2TP_HDR_OFF) != 0))) { /* offset field */
812 priv->stats.recvRunts++;
813 NG_FREE_ITEM(item);
814 NG_FREE_M(m);
815 ERROUT(EINVAL);
816 }
817
818 /* Get and validate length field if present */
819 if ((hdr & L2TP_HDR_LEN) != 0) {
820 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
821 priv->stats.memoryFailures++;
822 NG_FREE_ITEM(item);
823 ERROUT(EINVAL);
824 }
825 len = (u_int16_t)ntohs(*mtod(m, u_int16_t *)) - 4;
826 m_adj(m, 2);
827 if (len < 0 || len > m->m_pkthdr.len) {
828 priv->stats.recvInvalid++;
829 NG_FREE_ITEM(item);
830 NG_FREE_M(m);
831 ERROUT(EINVAL);
832 }
833 if (len < m->m_pkthdr.len) /* trim extra bytes */
834 m_adj(m, -(m->m_pkthdr.len - len));
835 }
836
837 /* Get tunnel ID and session ID */
838 if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
839 priv->stats.memoryFailures++;
840 NG_FREE_ITEM(item);
841 ERROUT(EINVAL);
842 }
843 tid = (mtod(m, u_int8_t *)[0] << 8) + mtod(m, u_int8_t *)[1];
844 sid = (mtod(m, u_int8_t *)[2] << 8) + mtod(m, u_int8_t *)[3];
845 m_adj(m, 4);
846
847 /* Check tunnel ID */
848 if (tid != priv->conf.tunnel_id &&
849 (priv->conf.match_id || tid != 0)) {
850 priv->stats.recvWrongTunnel++;
851 NG_FREE_ITEM(item);
852 NG_FREE_M(m);
853 ERROUT(EADDRNOTAVAIL);
854 }
855
856 /* Check session ID (for data packets only) */
857 if ((hdr & L2TP_HDR_CTRL) == 0) {
858 hpriv = ng_l2tp_find_session(priv, sid);
859 if (hpriv == NULL) {
860 priv->stats.recvUnknownSID++;
861 NG_FREE_ITEM(item);
862 NG_FREE_M(m);
863 ERROUT(ENOTCONN);
864 }
865 hook = hpriv->hook;
866 }
867
868 /* Get Ns, Nr fields if present */
869 if ((hdr & L2TP_HDR_SEQ) != 0) {
870 if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
871 priv->stats.memoryFailures++;
872 NG_FREE_ITEM(item);
873 ERROUT(EINVAL);
874 }
875 ns = (mtod(m, u_int8_t *)[0] << 8) + mtod(m, u_int8_t *)[1];
876 nr = (mtod(m, u_int8_t *)[2] << 8) + mtod(m, u_int8_t *)[3];
877 m_adj(m, 4);
878 } else
879 ns = nr = 0;
880
881 /* Strip offset padding if present */
882 if ((hdr & L2TP_HDR_OFF) != 0) {
883 u_int16_t offset;
884
885 /* Get length of offset padding */
886 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
887 priv->stats.memoryFailures++;
888 NG_FREE_ITEM(item);
889 ERROUT(EINVAL);
890 }
891 offset = (mtod(m, u_int8_t *)[0] << 8) + mtod(m, u_int8_t *)[1];
892
893 /* Trim offset padding */
894 if ((2+offset) > m->m_pkthdr.len) {
895 priv->stats.recvInvalid++;
896 NG_FREE_ITEM(item);
897 NG_FREE_M(m);
898 ERROUT(EINVAL);
899 }
900 m_adj(m, 2+offset);
901 }
902
903 /* Handle control packets */
904 if ((hdr & L2TP_HDR_CTRL) != 0) {
905 struct l2tp_seq *const seq = &priv->seq;
906
907 /* Handle receive ack sequence number Nr */
908 ng_l2tp_seq_recv_nr(priv, nr);
909
910 /* Discard ZLB packets */
911 if (m->m_pkthdr.len == 0) {
912 priv->stats.recvZLBs++;
913 NG_FREE_ITEM(item);
914 NG_FREE_M(m);
915 ERROUT(0);
916 }
917
918 mtx_lock(&seq->mtx);
919 /*
920 * If not what we expect or we are busy, drop packet and
921 * send an immediate ZLB ack.
922 */
923 if (ns != seq->nr || seq->inproc) {
924 if (L2TP_SEQ_DIFF(ns, seq->nr) <= 0)
925 priv->stats.recvDuplicates++;
926 else
927 priv->stats.recvOutOfOrder++;
928 mtx_unlock(&seq->mtx);
929 ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
930 NG_FREE_ITEM(item);
931 NG_FREE_M(m);
932 ERROUT(0);
933 }
934 /*
935 * Until we deliver this packet we can't receive next one as
936 * we have no information for sending ack.
937 */
938 seq->inproc = 1;
939 mtx_unlock(&seq->mtx);
940
941 /* Prepend session ID to packet. */
942 M_PREPEND(m, 2, M_DONTWAIT);
943 if (m == NULL) {
944 seq->inproc = 0;
945 priv->stats.memoryFailures++;
946 NG_FREE_ITEM(item);
947 ERROUT(ENOBUFS);
948 }
949 mtod(m, u_int8_t *)[0] = sid >> 8;
950 mtod(m, u_int8_t *)[1] = sid & 0xff;
951
952 /* Deliver packet to upper layers */
953 NG_FWD_NEW_DATA(error, item, priv->ctrl, m);
954
955 mtx_lock(&seq->mtx);
956 /* Ready to process next packet. */
957 seq->inproc = 0;
958
959 /* If packet was successfully delivered send ack. */
960 if (error == 0) {
961 /* Update recv sequence number */
962 seq->nr++;
963 /* Start receive ack timer, if not already running */
964 if (!callout_active(&seq->xack_timer)) {
965 ng_callout(&seq->xack_timer, priv->node, NULL,
966 L2TP_DELAYED_ACK, ng_l2tp_seq_xack_timeout,
967 NULL, 0);
968 }
969 }
970 mtx_unlock(&seq->mtx);
971
972 ERROUT(error);
973 }
974
975 /* Per session packet, account it. */
976 hpriv->stats.recvPackets++;
977 hpriv->stats.recvOctets += plen;
978
979 /* Follow peer's lead in data sequencing, if configured to do so */
980 if (!hpriv->conf.control_dseq)
981 hpriv->conf.enable_dseq = ((hdr & L2TP_HDR_SEQ) != 0);
982
983 /* Handle data sequence numbers if present and enabled */
984 if ((hdr & L2TP_HDR_SEQ) != 0) {
985 if (hpriv->conf.enable_dseq
986 && L2TP_SEQ_DIFF(ns, hpriv->nr) < 0) {
987 NG_FREE_ITEM(item); /* duplicate or out of order */
988 NG_FREE_M(m);
989 priv->stats.recvDataDrops++;
990 ERROUT(0);
991 }
992 hpriv->nr = ns + 1;
993 }
994
995 /* Drop empty data packets */
996 if (m->m_pkthdr.len == 0) {
997 NG_FREE_ITEM(item);
998 NG_FREE_M(m);
999 ERROUT(0);
1000 }
1001
1002 /* Deliver data */
1003 NG_FWD_NEW_DATA(error, item, hook, m);
1004 done:
1005 /* Done */
1006 L2TP_SEQ_CHECK(&priv->seq);
1007 return (error);
1008 }
1009
1010 /*
1011 * Handle an outgoing control frame.
1012 */
1013 static int
1014 ng_l2tp_rcvdata_ctrl(hook_p hook, item_p item)
1015 {
1016 const node_p node = NG_HOOK_NODE(hook);
1017 const priv_p priv = NG_NODE_PRIVATE(node);
1018 struct l2tp_seq *const seq = &priv->seq;
1019 struct mbuf *m;
1020 int error;
1021 int i;
1022 u_int16_t ns;
1023
1024 /* Sanity check */
1025 L2TP_SEQ_CHECK(&priv->seq);
1026
1027 /* If not configured, reject */
1028 if (!priv->conf.enabled) {
1029 NG_FREE_ITEM(item);
1030 ERROUT(ENXIO);
1031 }
1032
1033 /* Grab mbuf and discard other stuff XXX */
1034 NGI_GET_M(item, m);
1035 NG_FREE_ITEM(item);
1036
1037 /* Packet should have session ID prepended */
1038 if (m->m_pkthdr.len < 2) {
1039 priv->stats.xmitInvalid++;
1040 m_freem(m);
1041 ERROUT(EINVAL);
1042 }
1043
1044 /* Check max length */
1045 if (m->m_pkthdr.len >= 0x10000 - 14) {
1046 priv->stats.xmitTooBig++;
1047 m_freem(m);
1048 ERROUT(EOVERFLOW);
1049 }
1050
1051 mtx_lock(&seq->mtx);
1052
1053 /* Find next empty slot in transmit queue */
1054 for (i = 0; i < L2TP_MAX_XWIN && seq->xwin[i] != NULL; i++);
1055 if (i == L2TP_MAX_XWIN) {
1056 mtx_unlock(&seq->mtx);
1057 priv->stats.xmitDrops++;
1058 m_freem(m);
1059 ERROUT(ENOBUFS);
1060 }
1061 seq->xwin[i] = m;
1062
1063 /* If peer's receive window is already full, nothing else to do */
1064 if (i >= seq->cwnd) {
1065 mtx_unlock(&seq->mtx);
1066 ERROUT(0);
1067 }
1068
1069 /* Start retransmit timer if not already running */
1070 if (!callout_active(&seq->rack_timer))
1071 ng_callout(&seq->rack_timer, node, NULL,
1072 hz, ng_l2tp_seq_rack_timeout, NULL, 0);
1073
1074 ns = seq->ns++;
1075
1076 mtx_unlock(&seq->mtx);
1077
1078 /* Copy packet */
1079 if ((m = L2TP_COPY_MBUF(m, M_DONTWAIT)) == NULL) {
1080 priv->stats.memoryFailures++;
1081 ERROUT(ENOBUFS);
1082 }
1083
1084 /* Send packet and increment xmit sequence number */
1085 error = ng_l2tp_xmit_ctrl(priv, m, ns);
1086 done:
1087 /* Done */
1088 L2TP_SEQ_CHECK(&priv->seq);
1089 return (error);
1090 }
1091
1092 /*
1093 * Handle an outgoing data frame.
1094 */
1095 static int
1096 ng_l2tp_rcvdata(hook_p hook, item_p item)
1097 {
1098 const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
1099 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
1100 struct mbuf *m;
1101 u_int16_t hdr;
1102 int error;
1103 int i = 1;
1104
1105 /* Sanity check */
1106 L2TP_SEQ_CHECK(&priv->seq);
1107
1108 /* If not configured, reject */
1109 if (!priv->conf.enabled) {
1110 NG_FREE_ITEM(item);
1111 ERROUT(ENXIO);
1112 }
1113
1114 /* Get mbuf */
1115 NGI_GET_M(item, m);
1116
1117 /* Check max length */
1118 if (m->m_pkthdr.len >= 0x10000 - 12) {
1119 priv->stats.xmitDataTooBig++;
1120 NG_FREE_ITEM(item);
1121 NG_FREE_M(m);
1122 ERROUT(EOVERFLOW);
1123 }
1124
1125 /* Prepend L2TP header */
1126 M_PREPEND(m, 6
1127 + (2 * (hpriv->conf.include_length != 0))
1128 + (4 * (hpriv->conf.enable_dseq != 0)),
1129 M_DONTWAIT);
1130 if (m == NULL) {
1131 priv->stats.memoryFailures++;
1132 NG_FREE_ITEM(item);
1133 ERROUT(ENOBUFS);
1134 }
1135 hdr = L2TP_DATA_HDR;
1136 if (hpriv->conf.include_length) {
1137 hdr |= L2TP_HDR_LEN;
1138 mtod(m, u_int16_t *)[i++] = htons(m->m_pkthdr.len);
1139 }
1140 mtod(m, u_int16_t *)[i++] = htons(priv->conf.peer_id);
1141 mtod(m, u_int16_t *)[i++] = htons(hpriv->conf.peer_id);
1142 if (hpriv->conf.enable_dseq) {
1143 hdr |= L2TP_HDR_SEQ;
1144 mtod(m, u_int16_t *)[i++] = htons(hpriv->ns);
1145 mtod(m, u_int16_t *)[i++] = htons(hpriv->nr);
1146 hpriv->ns++;
1147 }
1148 mtod(m, u_int16_t *)[0] = htons(hdr);
1149
1150 /* Update per session stats. */
1151 hpriv->stats.xmitPackets++;
1152 hpriv->stats.xmitOctets += m->m_pkthdr.len;
1153
1154 /* And the global one. */
1155 priv->stats.xmitPackets++;
1156 priv->stats.xmitOctets += m->m_pkthdr.len;
1157
1158 /* Send packet */
1159 NG_FWD_NEW_DATA(error, item, priv->lower, m);
1160 done:
1161 /* Done */
1162 L2TP_SEQ_CHECK(&priv->seq);
1163 return (error);
1164 }
1165
1166 /*
1167 * Send a message to our controlling node that we've failed.
1168 */
1169 static void
1170 ng_l2tp_seq_failure(priv_p priv)
1171 {
1172 struct ng_mesg *msg;
1173 int error;
1174
1175 NG_MKMESSAGE(msg, NGM_L2TP_COOKIE, NGM_L2TP_ACK_FAILURE, 0, M_NOWAIT);
1176 if (msg == NULL)
1177 return;
1178 NG_SEND_MSG_ID(error, priv->node, msg, priv->ftarget, 0);
1179 }
1180
1181 /************************************************************************
1182 SEQUENCE NUMBER HANDLING
1183 ************************************************************************/
1184
1185 /*
1186 * Initialize sequence number state.
1187 */
1188 static void
1189 ng_l2tp_seq_init(priv_p priv)
1190 {
1191 struct l2tp_seq *const seq = &priv->seq;
1192
1193 KASSERT(priv->conf.peer_win >= 1,
1194 ("%s: peer_win is zero", __func__));
1195 memset(seq, 0, sizeof(*seq));
1196 seq->cwnd = 1;
1197 seq->wmax = priv->conf.peer_win;
1198 if (seq->wmax > L2TP_MAX_XWIN)
1199 seq->wmax = L2TP_MAX_XWIN;
1200 seq->ssth = seq->wmax;
1201 ng_callout_init(&seq->rack_timer);
1202 ng_callout_init(&seq->xack_timer);
1203 mtx_init(&seq->mtx, "ng_l2tp", NULL, MTX_DEF);
1204 L2TP_SEQ_CHECK(seq);
1205 }
1206
1207 /*
1208 * Set sequence number state as given from user.
1209 */
1210 static int
1211 ng_l2tp_seq_set(priv_p priv, const struct ng_l2tp_seq_config *conf)
1212 {
1213 struct l2tp_seq *const seq = &priv->seq;
1214
1215 /* If node is enabled, deny update to sequence numbers. */
1216 if (priv->conf.enabled)
1217 return (EBUSY);
1218
1219 /* We only can handle the simple cases. */
1220 if (conf->xack != conf->nr || conf->ns != conf->rack)
1221 return (EINVAL);
1222
1223 /* Set ns,nr,rack,xack parameters. */
1224 seq->ns = conf->ns;
1225 seq->nr = conf->nr;
1226 seq->rack = conf->rack;
1227 seq->xack = conf->xack;
1228
1229 return (0);
1230 }
1231
1232 /*
1233 * Adjust sequence number state accordingly after reconfiguration.
1234 */
1235 static int
1236 ng_l2tp_seq_adjust(priv_p priv, const struct ng_l2tp_config *conf)
1237 {
1238 struct l2tp_seq *const seq = &priv->seq;
1239 u_int16_t new_wmax;
1240
1241 /* If disabling node, reset state sequence number */
1242 if (!conf->enabled) {
1243 ng_l2tp_seq_reset(priv);
1244 return (0);
1245 }
1246
1247 /* Adjust peer's max recv window; it can only increase */
1248 new_wmax = conf->peer_win;
1249 if (new_wmax > L2TP_MAX_XWIN)
1250 new_wmax = L2TP_MAX_XWIN;
1251 if (new_wmax == 0)
1252 return (EINVAL);
1253 if (new_wmax < seq->wmax)
1254 return (EBUSY);
1255 seq->wmax = new_wmax;
1256
1257 /* Done */
1258 return (0);
1259 }
1260
1261 /*
1262 * Reset sequence number state.
1263 */
1264 static void
1265 ng_l2tp_seq_reset(priv_p priv)
1266 {
1267 struct l2tp_seq *const seq = &priv->seq;
1268 hook_p hook;
1269 int i;
1270
1271 /* Sanity check */
1272 L2TP_SEQ_CHECK(seq);
1273
1274 /* Stop timers */
1275 ng_uncallout(&seq->rack_timer, priv->node);
1276 ng_uncallout(&seq->xack_timer, priv->node);
1277
1278 /* Free retransmit queue */
1279 for (i = 0; i < L2TP_MAX_XWIN; i++) {
1280 if (seq->xwin[i] == NULL)
1281 break;
1282 m_freem(seq->xwin[i]);
1283 }
1284
1285 /* Reset session hooks' sequence number states */
1286 NG_NODE_FOREACH_HOOK(priv->node, ng_l2tp_reset_session, NULL, hook);
1287
1288 /* Reset node's sequence number state */
1289 seq->ns = 0;
1290 seq->nr = 0;
1291 seq->rack = 0;
1292 seq->xack = 0;
1293 seq->wmax = L2TP_MAX_XWIN;
1294 seq->cwnd = 1;
1295 seq->ssth = seq->wmax;
1296 seq->acks = 0;
1297 seq->rexmits = 0;
1298 bzero(seq->xwin, sizeof(seq->xwin));
1299
1300 /* Done */
1301 L2TP_SEQ_CHECK(seq);
1302 }
1303
1304 /*
1305 * Handle receipt of an acknowledgement value (Nr) from peer.
1306 */
1307 static void
1308 ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr)
1309 {
1310 struct l2tp_seq *const seq = &priv->seq;
1311 struct mbuf *xwin[L2TP_MAX_XWIN]; /* partial local copy */
1312 int nack;
1313 int i, j;
1314 uint16_t ns;
1315
1316 mtx_lock(&seq->mtx);
1317
1318 /* Verify peer's ACK is in range */
1319 if ((nack = L2TP_SEQ_DIFF(nr, seq->rack)) <= 0) {
1320 mtx_unlock(&seq->mtx);
1321 return; /* duplicate ack */
1322 }
1323 if (L2TP_SEQ_DIFF(nr, seq->ns) > 0) {
1324 mtx_unlock(&seq->mtx);
1325 priv->stats.recvBadAcks++; /* ack for packet not sent */
1326 return;
1327 }
1328 KASSERT(nack <= L2TP_MAX_XWIN,
1329 ("%s: nack=%d > %d", __func__, nack, L2TP_MAX_XWIN));
1330
1331 /* Update receive ack stats */
1332 seq->rack = nr;
1333 seq->rexmits = 0;
1334
1335 /* Free acknowledged packets and shift up packets in the xmit queue */
1336 for (i = 0; i < nack; i++)
1337 m_freem(seq->xwin[i]);
1338 memmove(seq->xwin, seq->xwin + nack,
1339 (L2TP_MAX_XWIN - nack) * sizeof(*seq->xwin));
1340 memset(seq->xwin + (L2TP_MAX_XWIN - nack), 0,
1341 nack * sizeof(*seq->xwin));
1342
1343 /*
1344 * Do slow-start/congestion avoidance windowing algorithm described
1345 * in RFC 2661, Appendix A. Here we handle a multiple ACK as if each
1346 * ACK had arrived separately.
1347 */
1348 if (seq->cwnd < seq->wmax) {
1349
1350 /* Handle slow start phase */
1351 if (seq->cwnd < seq->ssth) {
1352 seq->cwnd += nack;
1353 nack = 0;
1354 if (seq->cwnd > seq->ssth) { /* into cg.av. phase */
1355 nack = seq->cwnd - seq->ssth;
1356 seq->cwnd = seq->ssth;
1357 }
1358 }
1359
1360 /* Handle congestion avoidance phase */
1361 if (seq->cwnd >= seq->ssth) {
1362 seq->acks += nack;
1363 while (seq->acks >= seq->cwnd) {
1364 seq->acks -= seq->cwnd;
1365 if (seq->cwnd < seq->wmax)
1366 seq->cwnd++;
1367 }
1368 }
1369 }
1370
1371 /* Stop xmit timer */
1372 if (callout_active(&seq->rack_timer))
1373 ng_uncallout(&seq->rack_timer, priv->node);
1374
1375 /* If transmit queue is empty, we're done for now */
1376 if (seq->xwin[0] == NULL) {
1377 mtx_unlock(&seq->mtx);
1378 return;
1379 }
1380
1381 /* Start restransmit timer again */
1382 ng_callout(&seq->rack_timer, priv->node, NULL,
1383 hz, ng_l2tp_seq_rack_timeout, NULL, 0);
1384
1385 /*
1386 * Send more packets, trying to keep peer's receive window full.
1387 * Make copy of everything we need before lock release.
1388 */
1389 ns = seq->ns;
1390 j = 0;
1391 while ((i = L2TP_SEQ_DIFF(seq->ns, seq->rack)) < seq->cwnd
1392 && seq->xwin[i] != NULL) {
1393 xwin[j++] = seq->xwin[i];
1394 seq->ns++;
1395 }
1396
1397 mtx_unlock(&seq->mtx);
1398
1399 /*
1400 * Send prepared.
1401 * If there is a memory error, pretend packet was sent, as it
1402 * will get retransmitted later anyway.
1403 */
1404 for (i = 0; i < j; i++) {
1405 struct mbuf *m;
1406 if ((m = L2TP_COPY_MBUF(xwin[i], M_DONTWAIT)) == NULL)
1407 priv->stats.memoryFailures++;
1408 else
1409 ng_l2tp_xmit_ctrl(priv, m, ns);
1410 ns++;
1411 }
1412 }
1413
1414 /*
1415 * Handle an ack timeout. We have an outstanding ack that we
1416 * were hoping to piggy-back, but haven't, so send a ZLB.
1417 */
1418 static void
1419 ng_l2tp_seq_xack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
1420 {
1421 const priv_p priv = NG_NODE_PRIVATE(node);
1422 struct l2tp_seq *const seq = &priv->seq;
1423
1424 /* Make sure callout is still active before doing anything */
1425 if (callout_pending(&seq->xack_timer) ||
1426 (!callout_active(&seq->xack_timer)))
1427 return;
1428
1429 /* Sanity check */
1430 L2TP_SEQ_CHECK(seq);
1431
1432 /* Send a ZLB */
1433 ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
1434
1435 /* callout_deactivate() is not needed here
1436 as ng_uncallout() was called by ng_l2tp_xmit_ctrl() */
1437
1438 /* Sanity check */
1439 L2TP_SEQ_CHECK(seq);
1440 }
1441
1442 /*
1443 * Handle a transmit timeout. The peer has failed to respond
1444 * with an ack for our packet, so retransmit it.
1445 */
1446 static void
1447 ng_l2tp_seq_rack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
1448 {
1449 const priv_p priv = NG_NODE_PRIVATE(node);
1450 struct l2tp_seq *const seq = &priv->seq;
1451 struct mbuf *m;
1452 u_int delay;
1453
1454 /* Make sure callout is still active before doing anything */
1455 if (callout_pending(&seq->rack_timer) ||
1456 (!callout_active(&seq->rack_timer)))
1457 return;
1458
1459 /* Sanity check */
1460 L2TP_SEQ_CHECK(seq);
1461
1462 priv->stats.xmitRetransmits++;
1463
1464 /* Have we reached the retransmit limit? If so, notify owner. */
1465 if (seq->rexmits++ >= priv->conf.rexmit_max)
1466 ng_l2tp_seq_failure(priv);
1467
1468 /* Restart timer, this time with an increased delay */
1469 delay = (seq->rexmits > 12) ? (1 << 12) : (1 << seq->rexmits);
1470 if (delay > priv->conf.rexmit_max_to)
1471 delay = priv->conf.rexmit_max_to;
1472 ng_callout(&seq->rack_timer, node, NULL,
1473 hz * delay, ng_l2tp_seq_rack_timeout, NULL, 0);
1474
1475 /* Do slow-start/congestion algorithm windowing algorithm */
1476 seq->ns = seq->rack;
1477 seq->ssth = (seq->cwnd + 1) / 2;
1478 seq->cwnd = 1;
1479 seq->acks = 0;
1480
1481 /* Retransmit oldest unack'd packet */
1482 if ((m = L2TP_COPY_MBUF(seq->xwin[0], M_DONTWAIT)) == NULL)
1483 priv->stats.memoryFailures++;
1484 else
1485 ng_l2tp_xmit_ctrl(priv, m, seq->ns++);
1486
1487 /* callout_deactivate() is not needed here
1488 as ng_callout() is getting called each time */
1489
1490 /* Sanity check */
1491 L2TP_SEQ_CHECK(seq);
1492 }
1493
1494 /*
1495 * Transmit a control stream packet, payload optional.
1496 * The transmit sequence number is not incremented.
1497 */
1498 static int
1499 ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns)
1500 {
1501 struct l2tp_seq *const seq = &priv->seq;
1502 u_int16_t session_id = 0;
1503 int error;
1504
1505 mtx_lock(&seq->mtx);
1506
1507 /* Stop ack timer: we're sending an ack with this packet.
1508 Doing this before to keep state predictable after error. */
1509 if (callout_active(&seq->xack_timer))
1510 ng_uncallout(&seq->xack_timer, priv->node);
1511
1512 seq->xack = seq->nr;
1513
1514 mtx_unlock(&seq->mtx);
1515
1516 /* If no mbuf passed, send an empty packet (ZLB) */
1517 if (m == NULL) {
1518
1519 /* Create a new mbuf for ZLB packet */
1520 MGETHDR(m, M_DONTWAIT, MT_DATA);
1521 if (m == NULL) {
1522 priv->stats.memoryFailures++;
1523 return (ENOBUFS);
1524 }
1525 m->m_len = m->m_pkthdr.len = 12;
1526 m->m_pkthdr.rcvif = NULL;
1527 priv->stats.xmitZLBs++;
1528 } else {
1529
1530 /* Strip off session ID */
1531 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
1532 priv->stats.memoryFailures++;
1533 return (ENOBUFS);
1534 }
1535 session_id = (mtod(m, u_int8_t *)[0] << 8) + mtod(m, u_int8_t *)[1];
1536
1537 /* Make room for L2TP header */
1538 M_PREPEND(m, 10, M_DONTWAIT); /* - 2 + 12 = 10 */
1539 if (m == NULL) {
1540 priv->stats.memoryFailures++;
1541 return (ENOBUFS);
1542 }
1543 }
1544
1545 /* Fill in L2TP header */
1546 mtod(m, u_int16_t *)[0] = htons(L2TP_CTRL_HDR);
1547 mtod(m, u_int16_t *)[1] = htons(m->m_pkthdr.len);
1548 mtod(m, u_int16_t *)[2] = htons(priv->conf.peer_id);
1549 mtod(m, u_int16_t *)[3] = htons(session_id);
1550 mtod(m, u_int16_t *)[4] = htons(ns);
1551 mtod(m, u_int16_t *)[5] = htons(seq->nr);
1552
1553 /* Update sequence number info and stats */
1554 priv->stats.xmitPackets++;
1555 priv->stats.xmitOctets += m->m_pkthdr.len;
1556
1557 /* Send packet */
1558 NG_SEND_DATA_ONLY(error, priv->lower, m);
1559 return (error);
1560 }
1561
1562 #ifdef INVARIANTS
1563 /*
1564 * Sanity check sequence number state.
1565 */
1566 static void
1567 ng_l2tp_seq_check(struct l2tp_seq *seq)
1568 {
1569 int self_unack, peer_unack;
1570 int i;
1571
1572 #define CHECK(p) KASSERT((p), ("%s: not: %s", __func__, #p))
1573
1574 mtx_lock(&seq->mtx);
1575
1576 self_unack = L2TP_SEQ_DIFF(seq->nr, seq->xack);
1577 peer_unack = L2TP_SEQ_DIFF(seq->ns, seq->rack);
1578 CHECK(seq->wmax <= L2TP_MAX_XWIN);
1579 CHECK(seq->cwnd >= 1);
1580 CHECK(seq->cwnd <= seq->wmax);
1581 CHECK(seq->ssth >= 1);
1582 CHECK(seq->ssth <= seq->wmax);
1583 if (seq->cwnd < seq->ssth)
1584 CHECK(seq->acks == 0);
1585 else
1586 CHECK(seq->acks <= seq->cwnd);
1587 CHECK(self_unack >= 0);
1588 CHECK(peer_unack >= 0);
1589 CHECK(peer_unack <= seq->wmax);
1590 CHECK((self_unack == 0) ^ callout_active(&seq->xack_timer));
1591 CHECK((peer_unack == 0) ^ callout_active(&seq->rack_timer));
1592 for (i = 0; i < peer_unack; i++)
1593 CHECK(seq->xwin[i] != NULL);
1594 for ( ; i < seq->cwnd; i++) /* verify peer's recv window full */
1595 CHECK(seq->xwin[i] == NULL);
1596
1597 mtx_unlock(&seq->mtx);
1598
1599 #undef CHECK
1600 }
1601 #endif /* INVARIANTS */
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